Hubble Telescope Finds Water Signals on 5 Distant Planets
A few days ago, NASA stated that "discrete water signals" were found in the atmosphere of five planets outside the solar system, indicating the next step in developing planetary searches that are capable of sustaining alien life.
The presence of water in the atmosphere of exoplanets had been previously recorded, but NASA believes this study is the first to “conclusively measure and compare” the light signals that denote the existence of water.
“We are very confident that we have found water signs on several planets. This work really opens the door to comparing how much water is present in the atmospheres of different types of exoplanets, such as hot versus cold, for example, ”says Avi Mandell, NASA planetary scientist and author of the paper that was published earlier this month in the journal. Astrophysical Journal.
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The presence of water
The five planets in question - WASP-17b, HD209458b, WASP-12b, WASP-19b and XO-1b - are known as “hot Jupiter”: a class of extrasolar planets that orbit very close to a star and therefore have temperatures. very high on the surface.
The five planets analyzed by the scientists showed clear signs of water, although the strongest evidence was on the surface of WASP-17b and HD209458b.
“Accurately detecting the atmosphere of an exoplanet is extraordinarily difficult. But we could find a very clear sign, and it's water, ”says Drake Deming, a researcher at the University of Maryland.
The scientific explanation
To explain how the research that resulted in this discovery took place, NASA released a very didactic video. In it, the space agency recalls that it is difficult to get information about these planets. For this reason, less than 5% of exoplanets were observed directly, and much of what we know comes from observing the changes that occur in starlight as the planet passes.
When an exoplanet is in transit, it blocks a small amount of light emitted by the star it orbits. By carefully measuring the amount of light blocked, scientists can determine the size of the planet. Following the same reasoning, it can be noted that the exoplanet blocks different parts of the color spectrum depending on its composition. And because we know that different molecules absorb different wavelengths, changes in the spectrum help identify the composition of the star.
To find traces of water vapor in atmospheres, Deming and his team used the field view of Hubble's camera 3, which is capable of measuring near infrared rays. The scientists waited until each of the planets passed in front of their star and then pointed Hubble at them. Because water molecules absorb certain wavelengths of light, the researchers were able to detect the presence of water vapor during planet transit by measuring unabsorbed wavelengths through Hubble.